Sometimes you might need to sumbmit electronically signed documents to Estonian authorities or service providers. When a document cannot be signed directly in your browser you would need to use a desktop computer or a mobile app for adding a signature on your device.
To sign digitally you would need Estonian ID-card, Smart-ID or Mobile-ID and DigiDoc4 software.
A digital signature is an electronic signature that has the same legal validity as a handwritten signature. Authorities only accept QES (Qualified Electronic Signature) level electronic signatures that by now are the standard in Estonia for all signing methods since November 2018. Before that Smart-ID did not qualify for QES.
For adding a signature in your desktop computer follow the advice here.
For adding a signature on your mobile device follow the advice here.
The electronically signed file would be saved on your device as Associated Signature Containers (ASiC) format file. This is the file format you need to submit after successfully signing a document.